Amino Acid Catabolism: An Overlooked Area of Metabolism.

Amino acids have been extensively studied in nutrition, mainly as key elements for maintaining optimal protein synthesis in the body as well as precursors of various nitrogen-containing compounds. However, it is now known that amino acid catabolism is an important element for the metabolic control of different biological processes, although it is still a developing field to have a deeper understanding of its biological implications. The mechanisms involved in the regulation of amino acid catabolism now include the contribution of the gut microbiota to amino acid oxidation and metabolite generation in the intestine, the molecular mechanisms of transcriptional control, and the participation of specific miRNAs involved in the regulation of amino acid degrading enzymes. In addition, molecules derived from amino acid catabolism play a role in metabolism as they are used in the epigenetic regulation of many genes. Thus, this review aims to examine the mechanisms of amino acid catabolism and to support the idea that this process is associated with the immune response, abnormalities during obesity, in particular insulin resistance, and the regulation of thermogenesis.

Effect of hydric stress-related acoustic emission on transcriptional and biochemical changes associated with a water deficit in Capsicum annuum L.

At specific vibration frequencies like ones generated by insects such as caterpillar chewing and bee's buzz-pollination turn on the plants secondary metabolism and their respective pathways gets activated. Thus, studies report that vibrations and sound waves applied to plants improves their fitness performance. Commonly, acoustic treatments for plants have used arbitrarily random frequencies. In this work, a group of signals obtained from hydric-stressed plants was recorded as vibrational patterns using a laser vibrometer. These vibration-signals were classified as representative of each condition and then externally applied as Acoustic Emission Patterns (AEP). The present research hypothesized that specific vibration frequencies could "emulate" a plant signal through mechanical energy based on tplant's ability to recognize vibration pattern similarity to a hydric status. This investigation aimed to apply the AEP's as characteristic vibrations classified as Low hydric stress (LHS), medium hydric stress (MHS), and high hydric stress (HHS) to evaluate their effect on healthy-well watered plants at two developmental stages. In the vegetative stage, the gene expression related to antioxidant and hydric stress responses was assessed. The LHS, MHS, and HHS acoustic treatments up-regulated the peroxidase (Pod) (~2.8, 1.9, and 3.6-fold change, respectively). The superoxide dismutase (Mn-sod) and phenylalanine ammonia-lyase (Pal) genes were up-regulated by HHS (~0.23 and ~0.55-fold change, respectively) and, the chalcone synthase (Chs) gene was induced by MHS (~0.63-fold-change). At the fructification stage, the MHS treatment induced a significant increase in Capsaicin content (5.88-fold change), probably through the at3and kas gene activation. Findings are correlated for a better understanding of plant responses to different multi frequency-signals tones from vibrations with potential for agricultural applications.

Gene and systemic inflammatory effects and neuroendocrine response in surgical patients anesthetized with desflurane-nitrous oxide or desflurane-nitrous oxide-free: A randomized trial.

There is growing interest in assessing possible immunotoxicological effects in anesthetized patients. There are controversial findings concerning the effect of nitrous oxide (N2O) anesthetic gas effect on inflammatory response. We tested the hypothesis that N2O associated with desflurane (inhalational anesthetic) was likely to worsen neuro-immune-endocrine effects when compared with desflurane alone in this randomized trial. The primary endpoint of this study was to evaluate the systemic proinflammatory interleukin (IL)-6, and the secondary endpoints included other systemic (IL-1ß, TNF-α, IL-8, IL-10, IL-17A and high-sensitivity C-reactive protein - hs-CRP) and genetic inflammatory markers (NF-kB, IL-6 and COX-2) as well as hormones (adrenocorticotropic hormone, cortisol and prolactin) comparing patients undergoing minor surgery with or without N2O-desflurane. As a second aim, we assessed whether there were changes in the neuro-immune-endocrine profiles within each group. Blood samples were collected before anesthesia, 90 min after anesthesia induction, and the day after surgery. We assessed serum cytokines using a cytometric bead array and hs-CRP by chemiluminescent immunoassay. Expression of three proinflammatory transcripts was assessed by real-time quantitative polymerase chain reaction, and neuroendocrine hormones were detected by chemiluminescent microparticle immunoenzymatic assay. There were no significant between-group differences for any analyzed biomarkers. However, there was a significant increase in: (a) systemic IL-6 and hs-CRP values one day after surgery in both groups and (b) prolactin levels in the intraoperative period compared to baseline and postoperative period levels for both groups. In conclusion, N2O does not impair the inflammatory profile and neuroendocrine response compared to patients who receive only desflurane anesthesia.

Epigenetic silencing of the osteoblast-lineage gene program during hippocampal maturation.

Accumulating evidence indicates that epigenetic control of gene expression plays a significant role during cell lineage commitment and subsequent cell fate maintenance. Here, we assess epigenetic mechanisms operating in the rat brain that mediate silencing of genes that are expressed during early and late stages of osteogenesis. We report that repression of the osteoblast master regulator Sp7 in embryonic (E18) hippocampus is mainly mediated through the Polycomb complex PRC2 and its enzymatic product H3K27me3. During early postnatal (P10), juvenile (P30), and adult (P90) hippocampal stages, the repressive H3K27me3 mark is progressively replaced by nucleosome enrichment and increased CpG DNA methylation at the Sp7 gene promoter. In contrast, silencing of the late bone phenotypic Bglap gene in the hippocampus is PRC2-independent and accompanied by strong CpG methylation from E18 through postnatal and adult stages. Forced ectopic expression of the primary master regulator of osteogenesis Runx2 in embryonic hippocampal neurons activates the expression of its downstream target Sp7 gene. Moreover, transcriptomic analyses show that several genes associated with the mesenchymal-osteogenic lineages are transcriptionally activated in these hippocampal cells that express Runx2 and Sp7. This effect is accompanied by a loss in neuronal properties, including a significant reduction in secondary processes at the dendritic arbor and reduced expression of critical postsynaptic genes like PSD95. Together, our results reveal a developmental progression in epigenetic control mechanisms that repress the expression of the osteogenic program in hippocampal neurons at embryonic, postnatal, and adult stages.

Analysis of the endometrial transcriptome at the time of implantation in women receiving a single post-ovulatory dose of levonorgestrel or mifepristone

Abstract Background: Levonorgestrel (LNG) is a progesterone receptor agonist used in both regular and emergency hormonal contraception; however, its effects on the endometrium as a contraceptive remain widely unknown and under public debate. Objective: To analyze the effects of LNG or mifepristone (MFP), a progesterone receptor antagonist and also known as RU-486, administered at the time of follicle rupture (FR) on endometrial transcriptome during the receptive period of the menstrual cycle. Methods: Ten volunteers ovulatory women were studied during two menstrual cycles, a control cycle and a consecutively treated cycle; in this last case, women were randomly allocated to two groups of 5 women each, receiving one dose of LNG (1.5 mg) or MFP (50 mg) the day of the FR by ultrasound. Endometrial biopsies were taken 6 days after drug administration and prepared for microarray analysis. Results: Genomic functional analysis in the LNG-treated group showed as activated the bio-functions embryo implantation and decidualization, while these bio-functions in the T-MFP group were predicted as inhibited. Conclusions: The administration of LNG as a hormonal emergency contraceptive resulted in an endometrial gene expression profile associated with receptivity. These results agree on the concept that LNG does not affect endometrial receptivity and/or embryo implantation when used as an emergency contraceptive.

Consumption of minas frescal cheese may be a source of human infection by Campylobacter jejuni / Consumo de queijo minas frescal pode ser fonte de infecção humana por Campylobacter jejuni

Campylobacter spp. is an emerging pathogen that causes gastroenteritis in humans and the consumption of dairy food can characterize sources of infection. We aimed to verify the viability and a presence of transcripts associated with characteristics of virulence and adaptation of C. jejuni isolated from Minas Frescal cheeses, produced with contaminated milk and stored under refrigeration for up to ten days. The samples were analyzed for bioindicators, Campylobacter spp., pH, acidity, moisture and sodium chloride. Campylobacter spp. recovered were evaluated for the production of transcripts of: ciaB, dnaJ, p19 and sodB. The results were correlated with the viability of C. jejuni and changes in their transcriptome. Storage at lowtemperatures reduced C. jejuni from the first to the fourth day. The variations in humidity, pH and acidity influenced the decreasing of C. jejuni. There was a reduction in transcripts' production of the four genes, more pronounced on the fourth day, indicating the inability of the microorganism to perform its metabolic activities, due to the conditions of injury. Despite the presence of mechanisms of virulence and adaptation, C. jejuni could not remain viable four days after production. However, consumption of fresh cheese contaminated with Campylobacter jejuni can be a source of infection when consumed up to four days after production.

Campylobacter spp. é um patógeno emergente que causa gastroenterite em seres humanos e o consumo de produtos lácteos pode caracterizar fontes de infecção. O objetivo deste estudo foi verificar a viabilidade e a presença de transcritos associadas a características de virulência e adaptação de C. jejuniisoladas de queijos frescos, produzidos com leite contaminado e mantidos refrigeradas por dez dias. Foram analisados bioindicadores, Campylobacter spp., pH, acidez, umidade e cloreto de sódio. Campylobacter spp. recuperados foram avaliados quanto à produção dos transcritos: ciaB, dnaJ, p19 e sodB. Os resultados foram correlacionados com a viabilidade de C. jejuni e alterações no transcriptoma. O armazenamento em baixas temperaturas reduziu C. jejuni do primeiro ao quarto dia. As variações na umidade, pH e acidez influenciaram a queda de C. jejuni. Houve uma redução na produção de transcritos dos quatro genes, mais pronunciada no quarto dia, indicando a incapacidade do micro-organismo em realizar suas atividades metabólicas, devido às condições de injúria. Apesar da presença de mecanismos de virulência e adaptação, C. jejuni não permaneceu viável quatro dias após a produção. Porém, o consumo de queijo fresco contaminado com Campylobacter jejunipode ser uma fonte de infecção quando consumido até quatro dias após a produção.

Ezh2-dependent H3K27me3 modification dynamically regulates vitamin D3-dependent epigenetic control of CYP24A1 gene expression in osteoblastic cells.

Epigenetic control is critical for the regulation of gene transcription in mammalian cells. Among the most important epigenetic mechanisms are those associated with posttranslational modifications of chromosomal histone proteins, which modulate chromatin structure and increased accessibility of promoter regulatory elements for competency to support transcription. A critical histone mark is trimethylation of histone H3 at lysine residue 27 (H3K27me3), which is mediated by Ezh2, the catalytic subunit of the polycomb group complex PRC2 to repress transcription. Treatment of cells with the active vitamin D metabolite 1,25(OH)2 D3 , results in transcriptional activation of the CYP24A1 gene, which encodes a 24-hydroxylase enzyme, that is, essential for physiological control of vitamin D3 levels. We report that the Ezh2-mediated deposition of H3K27me3 at the CYP24A1 gene promoter is a requisite regulatory component during transcriptional silencing of this gene in osteoblastic cells in the absence of 1,25(OH)2 D3 . 1,25(OH)2 D3 dependent transcriptional activation of the CYP24A1 gene is accompanied by a rapid release of Ezh2 from the promoter, together with the binding of the H3K27me3-specific demethylase Utx/Kdm6a and thereby subsequent erasing of the H3K27me3 mark. Importantly, we find that these changes in H3K27me3 enrichment at the CYP24A1 gene promoter are highly dynamic, as this modification is rapidly reacquired following the withdrawal of 1,25(OH)2 D3 .

Switches in histone modifications epigenetically control vitamin D3-dependent transcriptional upregulation of the CYP24A1 gene in osteoblastic cells.

In bone cells vitamin D dependent regulation of gene expression principally occurs through modulation of gene transcription. Binding of the active vitamin D metabolite, 1,25-dihydroxy vitamin D3 (1,25(OH)2 D3 ) to the vitamin D receptor (VDR) induces conformational changes in its C-terminal domain enabling competency for interaction with physiologically relevant coactivators, including SRC-1. Consequently, regulatory complexes can be assembled that support intrinsic enzymatic activities with competency to posttranslationally modify chromatin histones at target genomic sequences to epigenetically alter transcription. Here we examine specific transitions in representation and/or enrichment of epigenetic histone marks during 1,25(OH)2 D3 mediated upregulation of CYP24A1 gene expression in osteoblastic cells. This gene encodes the 24-hydroxylase enzyme, essential for biological control of vitamin D levels. We demonstrate that as the CYP24A1 gene promoter remains transcriptionally silent, there is enrichment of H4R3me2s together with its "writing" enzyme PRMT5 and decreased abundance of the istone H3 and H4 acetylation, H3R17me2a, and H4R3me2a marks as well as of their corresponding "writers." Exposure of osteoblastic cells to 1,25(OH)2 D3 stimulates the recruitment of a VDR/SRC-1 containing complex to the CYP24A1 promoter to mediate increased H3/H4 acetylation. VDR/SRC-1 binding occurs concomitant with the release of PRMT5 and the recruitment of the arginine methyltransferases CARM1 and PRMT1 to catalyze the deposition of the H3R17me2a and H4R3me2a marks, respectively. Our results indicate that these dynamic transitions of histone marks at the CYP24A1 promoter, provide a "chromatin context" that is transcriptionally competent for activation of the CYP24A1 gene in osteoblastic cells in response to 1,25(OH)2 D3 .

ZO-2 Is a Master Regulator of Gene Expression, Cell Proliferation, Cytoarchitecture, and Cell Size.

ZO-2 is a cytoplasmic protein of tight junctions (TJs). Here, we describe ZO-2 involvement in the formation of the apical junctional complex during early development and in TJ biogenesis in epithelial cultured cells. ZO-2 acts as a scaffold for the polymerization of claudins at TJs and plays a unique role in the blood-testis barrier, as well as at TJs of the human liver and the inner ear. ZO-2 movement between the cytoplasm and nucleus is regulated by nuclear localization and exportation signals and post-translation modifications, while ZO-2 arrival at the cell border is triggered by activation of calcium sensing receptors and corresponding downstream signaling. Depending on its location, ZO-2 associates with junctional proteins and the actomyosin cytoskeleton or a variety of nuclear proteins, playing a role as a transcriptional repressor that leads to inhibition of cell proliferation and transformation. ZO-2 regulates cell architecture through modulation of Rho proteins and its absence induces hypertrophy due to inactivation of the Hippo pathway and activation of mTOR and S6K. The interaction of ZO-2 with viral oncoproteins and kinases and its silencing in diverse carcinomas reinforce the view of ZO-2 as a tumor regulator protein.

Increased grp78 transcription is correlated to reduced tlr4 transcription in patients surviving sepsis.

Regulated transcriptional readthrough during stress maintains genome structure and ensures access to genes that are necessary for cellular recovery. A broad number of genes, including of the bacterial sensor Toll-like receptor 4 (TLR-4), are markedly transcribed on initiating the systemic inflammatory response. Here we study the transcriptional patterns of tlr4 and of its modulator grp78 during human sepsis, and establish their correlations with the outcome of patients. We measured the daily tlr4 and grp78 RNA expression levels in peripheral blood of septic patients, immediately after admission to intensive care, and modeled these RNA values with a sine damping function. We obtained negative correlations between the transcription of tlr4 and grp78 RNA in the survivor group. In contrast, such relation is lost in the deceased patients. Loss of transcriptional homeostasis predicted by our model within the initial 4 days of hospitalization was confirmed by death of those patients up to 28 days later.

Stress responses in Crassostrea gasar exposed to combined effects of acute pH changes and phenanthrene.

Ocean acidification is a result of the decrease in the pH of marine water, caused mainly by the increase in CO2 released in the atmosphere and its consequent dissolution in seawater. These changes can be dramatic for marine organisms especially for oysters Crassostrea gasar if other stressors such as xenobiotics are present. The effect of pH changes (6.5, 7.0 and 8.2) was assessed on the transcript levels of biotransformation [cytochromes P450 (CYP2AU1, CYP2-like2) and glutathione S-transferase (GSTΩ-like)] and antioxidant [superoxide dismutase (SOD-like), catalase (CAT-like) and glutathione peroxidase (GPx-like)] genes, as well as enzyme activities [superoxide dismutase, (SOD), catalase (CAT), glutathione reductase (GR), glutathione-S-transferases transferase (GST) and glucose-6-phosphate dehydrogenase (G6PDH)] and lipid peroxidation (MDA) in the gills of Crassostrea gasar exposed to 100 µg·L-1 of phenanthrene (PHE) for 24 and 96 h. Likewise, the PHE burdens was evaluated in whole soft tissues of exposed oysters. The accumulation of PHE in oysters was independent of pH. However, acidification promoted a significant decrease in the transcript levels of some protective genes (24 h exposure: CYP2AU1 and GSTΩ-like; 96 h exposure: CAT-like and GPx-like), which was not observed in the presence of PHE. Activities of GST, CAT and SOD enzymes increased in the oysters exposed to PHE at the control pH (8.2), but at a lower pH values, this activation was suppressed, and no changes were observed in the G6PDH activity and MDA levels. Biotransformation genes showed better responses after 24 h, and antioxidant-coding genes after 96 h, along with the activities of antioxidant enzymes (SOD, CAT), probably because biotransformation of PHE increases the generation of reactive oxygen species. The lack of change in MDA levels suggests that antioxidant modulation efficiently prevented oxidative stress. The effect of pH on the responses to PHE exposure should be taken into account before using these and any other genes as potential molecular biomarkers for PHE exposure.

Mll-COMPASS complexes mediate H3K4me3 enrichment and transcription of the osteoblast master gene Runx2/p57 in osteoblasts.

Expression of Runx2/p57 is a hallmark of the osteoblast-lineage identity. Although several regulators that control the expression of Runx2/p57 during osteoblast-lineage commitment have been identified, the epigenetic mechanisms that sustain this expression in differentiated osteoblasts remain to be completely determined. Here, we assess epigenetic mechanisms associated with Runx2/p57 gene transcription in differentiating MC3T3 mouse osteoblasts. Our results show that an enrichment of activating histone marks at the Runx2/p57 P1 promoter is accompanied by the simultaneous interaction of Wdr5 and Utx proteins, both are components of COMPASS complexes. Knockdown of Wdr5 and Utx expression confirms the activating role of both proteins at the Runx2-P1 promoter. Other chromatin modifiers that were previously described to regulate Runx2/p57 transcription in mesenchymal precursor cells (Ezh2, Prmt5, and Jarid1b proteins) were not found to contribute to Runx2/p57 transcription in full-committed osteoblasts. We also determined the presence of additional components of COMPASS complexes at the Runx2/p57 promoter, evidencing that the Mll2/COMPASS- and Mll3/COMPASS-like complexes bind to the P1 promoter in osteoblastic cells expressing Runx2/p57 to modulate the H3K4me1 to H3K4me3 transition.

Phosphate Deficiency Negatively Affects Early Steps of the Symbiosis between Common Bean and Rhizobia.

Phosphate (Pi) deficiency reduces nodule formation and development in different legume species including common bean. Despite significant progress in the understanding of the genetic responses underlying the adaptation of nodules to Pi deficiency, it is still unclear whether this nutritional deficiency interferes with the molecular dialogue between legumes and rhizobia. If so, what part of the molecular dialogue is impaired? In this study, we provide evidence demonstrating that Pi deficiency negatively affects critical early molecular and physiological responses that are required for a successful symbiosis between common bean and rhizobia. We demonstrated that the infection thread formation and the expression of PvNSP2, PvNIN, and PvFLOT2, which are genes controlling the nodulation process were significantly reduced in Pi-deficient common bean seedlings. In addition, whole-genome transcriptional analysis revealed that the expression of hormones-related genes is compromised in Pi-deficient seedlings inoculated with rhizobia. Moreover, we showed that regardless of the presence or absence of rhizobia, the expression of PvRIC1 and PvRIC2, two genes participating in the autoregulation of nodule numbers, was higher in Pi-deficient seedlings compared to control seedlings. The data presented in this study provides a mechanistic model to better understand how Pi deficiency impacts the early steps of the symbiosis between common bean and rhizobia.

A single preovulatory administration of ulipristal acetate affects the decidualization process of the human endometrium during the receptive period of the menstrual cycle.

In order to get further information on the effects of ulipristal acetate (UPA) upon the process of decidualization of endometrium, a functional analysis of the differentially expressed genes in endometrium (DEG) from UPA treated-versus control-cycles of normal ovulatory women was performed. A list of 1183 endometrial DEG, from a previously published study by our group, was submitted to gene ontology, gene enrichment and ingenuity pathway analyses (IPA). This functional analysis showed that decidualization was a biological process overrepresented. Gene set enrichment analysis identified LIF, PRL, IL15 and STAT3 among the most down-regulated genes within the JAK STAT canonical pathway. IPA showed that decidualization of uterus was a bio-function predicted as inhibited by UPA. The results demonstrated that this selective progesterone receptor modulator, when administered during the periovulatory phase of the menstrual cycle, may affect the molecular mechanisms leading to endometrial decidualization in response to progesterone during the period of maximum embryo receptivity.

Effects of phenanthrene on early development of the Pacific oyster Crassostrea gigas (Thunberg, 1789).

Phenanthnere (PHE) is a polycyclic aromatic hydrocarbon continuously discarded in the marine environment and bioavailable to many aquatic species. Although studies about PHE toxicity have been documented for adult oysters, the effects on early developmental stages are poorly characterized in bivalves. In this study, the effects of PHE (0.02 and 2.0µg.L-1) were evaluated on the embryogenesis and larval development of Crassostrea gigas. Toxicity bioassays, growth and deformities assessment, analysis of shell calcium abundance and transcript levels of genes related to xenobiotic biotransformation (CYP2AU2, CYP30C1), immune system (Cg-Tal) and tissue growth and shell formation (Ferritin, Insulin-like, Cg-Try, Calmodulin and Nacrein) were assayed in D-shape larvae after 24h of PHE exposure. At the highest concentration (2.0µg.L-1), PHE decreased the frequency of normal development (19.7±2.9%) and shell size (53.5±2.8mm). Developmental deformities were mostly related to abnormal mantle and shell formation. Lower calcium levels in oyster shells exposed to PHE 2.0µg.L-1 were observed, suggesting effects on shell structure. At this same PHE concentration, CYP30C1, Cg-Tal, Cg-Tyr, Calmodulin were upregulated and CYP2AU2, Ferritin, Nacrein, and Insulin-Like were downregulated compared to control larvae. At the lowest PHE concentration (0.02µg.L-1), it was observed a minor decrease in normal larval development (89,6±6%) and the remaining parameters were not affected. This is the first study to provide evidences that exposure to PHE can affect early oyster development at the molecular and morphological levels, possibly threatening this bivalve species.

Different Phenotypes of Mature Biofilm in Flavobacterium psychrophilum Share a Potential for Virulence That Differs from Planktonic State.

Flavobacterium psychrophilum is the etiological agent of bacterial coldwater disease and the rainbow trout fry syndrome in salmonid aquaculture worldwide. However, there have been few studies into the capacity of F. psychrophilum to form biofilms and how these cellular accretions differ from planktonic cells or how they affect potential virulence. We evaluated the biofilm formation by three Chilean isolates of F. psychrophilum (LM-02-Fp, LM-06-Fp, and LM-13-Fp) and two non-Chilean strains (JIP02/86 and NCMB1947T), and compared biofilm and planktonic states to obtain insights into expression differences of virulence- and biofilm-related genes (VBRGs). Our findings are based on scanning confocal laser microscopy (SCLM) and LIVE/DEAD staining, enzymatic reactions, reverse transcription-quantitative PCR (RT-qPCR) of genes encoding putative virulence factors, and transcriptomes (RNA-Seq). The LM-02-Fp and NCMB1947T strains were the strongest and weakest biofilm producers, respectively. The strong-biofilm producer showed different physiological cell states distributed in different layers of mature biofilms, whereas the NCMB1947T biofilms consisted of cells arranged in a monolayer. WGA-binding exopolysaccharides would be the main components of their corresponding extracellular matrices. Transcriptomes of F. psychrophilum NCMB1947T and LM-02-Fp were clustered by state (biofilm vs. planktonic) rather than by strain, indicating important state-dependent differences in gene expression. Analysis of differentially expressed genes between states identified putative VBRGs involved in polysaccharide biosynthesis, lateral gene transfer, membrane transport (e.g., for drugs and Fe3+), sensory mechanisms, and adhesion, and indicated that about 60-100% of VBRGs involved in these processes was significantly upregulated in the biofilm state. Conversely, upregulated motility-related genes in the biofilm state were not identified, whereas a lower fraction of proteolysis-related genes (33%) was upregulated in biofilms. In summary, F. psychrophilum strains that produce different biofilm phenotypes show global transcriptional activity in the mature biofilm state that differs significantly from their planktonic counterparts. Also, different biofilm phenotypes share a genetic potential for virulence that is transcriptionally enhanced with respect to free-living cells. Our results suggest that the F. psychrophilum biofilm lifestyle acts as a reservoir for a given set of putative virulence factors, and recommend a deeper understanding of which could help prevent recurring infections in salmonid farms.

Molecular strategies to increase the levels of heterologous transcripts in Komagataella phaffii for protein production.

Komagataella phaffii (formerly Pichia pastoris) is a well-known fungal system for heterologous protein production in the context of modern biotechnology. To obtain higher protein titers in this system many researchers have sought to optimize gene expression by increasing the levels of transcription of the heterologous gene. This has been typically achieved by manipulating promoter sequences or by generating clones bearing multiple copies of the desired gene. The aim of this work is to describe how these different molecular strategies have been applied in K. phaffii presenting their advantages and drawbacks.

Epigenetics regulates transcription and pathogenesis in the parasite Trichomonas vaginalis.

Trichomonas vaginalis is a common sexually transmitted parasite that colonizes the human urogenital tract. Infections range from asymptomatic to highly inflammatory, depending on the host and the parasite strain. Different T. vaginalis strains vary greatly in their adherence and cytolytic capacities. These phenotypic differences might be attributed to differentially expressed genes as a consequence of extra-genetic variation, such as epigenetic modifications. In this study, we explored the role of histone acetylation in regulating gene transcription and pathogenesis in T. vaginalis. Here, we show that histone 3 lysine acetylation (H3KAc) is enriched in nucleosomes positioned around the transcription start site of active genes (BAP1 and BAP2) in a highly adherent parasite strain; compared with the low acetylation abundance in contrast to that observed in a less-adherent strain that expresses these genes at low levels. Additionally, exposition of less-adherent strain with a specific histone deacetylases inhibitor, trichostatin A, upregulated the transcription of BAP1 and BAP2 genes in concomitance with an increase in H3KAc abundance and chromatin accessibility around their transcription start sites. Moreover, we demonstrated that the binding of initiator binding protein, the transcription factor responsible for the initiation of transcription of ~75% of known T. vaginalis genes, depends on the histone acetylation state around the metazoan-like initiator to which initiator binding protein binds. Finally, we found that trichostatin A treatment increased parasite aggregation and adherence to host cells. Our data demonstrated for the first time that H3KAc is a permissive histone modification that functions to mediate both transcription and pathogenesis of the parasite T. vaginalis.

Principales promotores utilizados en la transformación genética de plantas / Main promoters used in plant genetic transformation

El conocimiento pleno de los promotores determina el éxito en la obtención de nuevos cultivares de plantas a través de técnicas biotecnológicas, ya que dicha secuencia del ADN regula la transcripción de otras regiones adyacentes o cercanas, encontrándose los siguientes promotores: constitutivos, tejido-específicos o estadio-específicos, inducibles y sintéticos. En esta revisión se resume de manera precisa los conceptos, ventajas y limitaciones de los distintos tipos de promotores, con ejemplos claros de ello.

Full knowledge of promoters determines success in obtaining new plant cultivars through biotechnology techniques. This DNA sequence regulates the transcription of adjacent or nearby regions, which are mainly constitutive, tissue-specific or stage-specific, inducible and synthetic. This review summarizes the precise concepts, advantages and limitations of different types of promoters, including clear examples of them.